Motorola Razr Maxx Big Issues

Hello everybody,
I have few major issues with my Motorola Droid Razr Maxx, running on Android 4.1.2 , system version 98.72.165.XT912.Verizon.en.US.
When I put my micro sim card in the slot and I start the phone, after entering my PIN code, everything seems okay, the phone accepts it. After approximately 1 minute, I'm getting a message, saying "Sim card is from an unknown source". The issue here is, that I can call and talk to anybody, but I can't receive calls. When I try to call my number from a different device, it just says, that the phone is switched off or outside network coverage. I tried playing with the Mobile Network settings. The only way I can receive calls is by setting Network mode to GSM/UMTS and in Select network to GSM Only. Data enabled is unticked, I don't see anything in Acess Point Names, Choose automatically option in Network operators is unticked too. That way, I do receive incoming calls, but I feel some disturbances in my earpiece, during the conversations. I thought, that the issue might be from my sim card, but today I got a brand new and the problems are the same. Please let me know, if I'm missing something in the options or if there is any solution to that issue.

My second very big issue is this: I'm experiencing some very nasty crackle sounds in my earpiece during calls (and skype/viber conversations too) . Also, some of the people I've talked say, that they don't hear me good enough, my voice is fading and they can't understand me from time to time. I read, that turning off the noise cancellation option and turning off voice privacy option might help, but I can't find any of those anywhere in the settings of my phone.

Please help me with those issues. I like the phone, but you'll agree, that those are some very serious problems, that just need to be solved, so the phone can be used in a normal way.